Electric switchgear



Jan. 24, 1956 J. A. JACKSON ET AL 2,732,452

' ELECTRIC SWITCHGEAR Filed NOV. 9, 1951 2 Sheets-Sheet 1 IVELBOt/RNEDEN/MR6? MLQ- HQ Ahorney Jan. 24, 1956 J. A. JACKSON ETAL 2,732,452

ELECTRIC SWITCHGEAR Filed Nov. 9, 1951 2 Sheets-Sheet 2 l mzo 20Inventors Jam's Aka-x7 J'nrmro/v r154 BOI/RIVE DEwflz/Rsr 8y MM 2. we

Attorney United States Patent O ELECTRIC SWITCHGEAR James A. Jackson,Hounslow, and Melbourne Dewlinrst, Cranford, Hounslow, England,assignors to Dewhnrst and Partner Limited, Hounslow, England, a Britishcompany Application November 9, 1951, Serial No. 255,584

4 Claims. (Cl. 200-87) The present invention relates to electricswitchgear and more particularly relates to contactor switches.

One object of the invention is the provision of improved constructionsof contactor switches.

One trouble which arises with existing constructions is that when thearmature closes, the contacts meet at high speed, and, due to themomentum of the moving contact attached to the armature, this contactbounces, which results in arcing. Such arcing, particularly in heavyduty work, seriously reduces the life of the contacts.

Accordingly, another object of the invention is to provide a novel andimproved electromagnetic contactor including cushioning or damping meansin form of a double pivoting arrangement which counteracts the tendencyof the moving contact to bounce away from the fixed contact therebyreducing or even completely eliminating the formation of arcs when thecontactor is actuated for closing its contacts. As a result, the usefullife of the contacts is appreciably prolonged.

One specific construction of contactor incorporating this feature willnow be described, by way of example only, with reference to theaccompanying drawings, in which:

Figure 1 is a side elevation of the contactor, one of the arc shieldsadjacent the contacts being shown removed for clarity, whilst Figure 2is an end elevation taken along the line Il-Il in Figure l.

In this construction the moving contact 19 is supported by a pair ofplates 11 of insulating material which are pivotally mounted near theirlower ends on a spindle 12 passing through the contactor armature 13,the plates 11 lying on opposite sides thereof. A second spindle 14 isalso fixed to the plates 11 and passes through a hole 13a in thearmature 13 near to the top of the latter, the diameter of the hole 13abeing somewhat larger than that of the spindle 14. The moving contact 10is mounted by a bracket 15 on a third spindle 16 fixed to the plates 11near their upper end, the moving contact 16 being normally maintained ata predetermined inclination by means of the usual compression spring 17which ensures a rolling and slight rubbing contact action when themoving contact 10 makes with the fixed contact 13. A pair of lightsprings 19 each fixed between one of the plates 11 and the armature 13normally maintain the plates 11 relative to the armature 13 in aposition such that the second spindle 14 engages that side of the hole13a in the armature 13 nearest to the contactor coil 29.

When the contacts 10 and 18 meet, the continued movement of the armature13 brings the second spindle 14 into engagement with the other side ofthe hole 13a (as shown in Figure 1), until the armature 13 engages thepole surface. Anytendency of the moving contact 10 to rebound iscounteracted by the plates 11 moving forward in relation to the armature13 under the control of the pair of light springs 19 until the momentumof the moving contact 10 and bracket 15 is absorbed by the spring 17.The design is such that the momentum is 2,732,452 Patented Jan. 24, 1956absorbed before the spindle 14 engages the side of the hole 13a nearestto the contactor coil 20. Thus, although the moving contact 10 tends tomove backwards away from the fixed contact 18, the sideplates 11 moveforward towards the contactor coil 20 and the moving contact 10 is keptin engagement with the fixed contact 18. This relative movement betweenthe armature 13 and the plates 11 is possible due to the enlarged hole13a through which the second spindle 14 passes.

A further feature of the invention is concerned with extinguishing theare drawn between the contacts 10 and 18 when they are interrupted.According to this feature a magnetic blow-out coil is connected betweena conductor from the fixed contact and an auxiliary contact mountedabove the fixed contact, whereby a blow-out coil is not energised whenthe contacts are made but is energised during breaking of the contactsdue to jumping of the are from the fixed contact to the auxiliarycontact.

in the embodiment of this arrangement which is shown in the drawin s, anauxiliary contact 21 is mounted above the fixed contact 13, and one endof a blow-out coil 22 is connected by a stud 23 to an electricallyconductive lead-in bracket 24 which supports this auxiliary contact 21.The other end of the blow-out coil 22 is connected by a stud 25 to thelead-in bracket 26 which supports the fixed contact 18.

With this arrangement drawing of the arc on breaking of the contactswill result in the arc jumping from the fixed contact 13 to theauxiliary contact 21, so that the arc current then flows through, andthus energises, the blow-out coil 22.

As the blow-out coil is only in circuit temporarily it can be of muchhigher rating than is normal, and the blow-out coil may be designed sothat the magnetic value obtained is much greater than usual.

The moving contact 10 may be arranged to drop back onto a secondauxiliary contact 27 of greater mass which, in the position when themoving contact 10 has fallen back (as shown in chain-dotted lines) ontothe second auxiliary contact 27, is nearer to the first auxiliarycontact 21 than the moving contact 10. With this arrangement the arc isthen transferred from the moving contact 10 to the second auxiliarycontact 27 which, due to the greater mass of the latter, can morereadily dissipate the heat generated.

According to another feature of the invention a plurality of discs offerrous material are mounted in the magnetic field of the blow-out coil,whereby on energisation of the blow-out coil the discs are magnetised tointensify the field acting to draw the arc.

in the embodiment illustrated, the discs 28 are mounted above theauxiliary contacts 21, 27.

The discs, which may for example be eight or ten in number, will alsohelp to quench the arc owing to their heat conducting properties.

What is claimed is:

1. An electromagnetic contactor, comprising a field member, an armaturemovably mounted on a fixed part, said armature being attractable to andreleasable from said field member, a carrier element pivotally mountedon said armature, a movable contact mounted on said carrier elementpivotal about an axis spaced apart from the axis of the carrier element,a relatively stationary fixed contact, first spring means biasing saidmovable contact relative to said carrier element, to a given limit inthe direction towards said fixed contact, and second spring meansbiasing said carrier element relative to said arma ture to a given limitin the direction to move said movable contact towards said fixedcontact, the movement of said armature, when attracted to said fieldmember, being in the direction to move said movable contact to saidfixed contact, whereby, upon engagement of said movable 3 contact withsaid fixed contact in response to the movement of said armataure to theattracted position, said second spring means initially yields before thearmature has reached its final position, and subsequently recovers,leaving said first spring means in a condition of yield.

2. An electromagnetic contactor, comprising a field member, an armaturemovably mounted on a fixed part, said armature being attractable to andreleasable from said field member, a carrier element pivotally mountedon said armature, a movable contact mounted on said carrier elementpivotal about an axis spaced apart from the axis of the carrier element,a relatively stationary fixed contact, first spring means biasing saidmovable contact relative to said carrier element, to a given limit inthe direction towards said fixed contact, and second spring meansbiasing said carrier element relative to said armature to a given limitin the direction to move said movable contact towards said fixedcontact, said carrier element being movable in opposition to said secondspring means to another given limit, the movement of said armature, whenattracted to said field member, being in the direction to move saidmovable contact to said fixed contact, whereby, upon engagement of saidmovable contact with said fixed contact in response to the movement ofsaid armature to the attracted position, said secondspring meansinitially yields to the extent of said other given limit of said carrierelement before the armature has reached its final position, andsubsequently recovers, leaving said first spring means in a condition ofyield.

3. An electromagnetic contactor, comprising a field member, an armaturemovably mounted on a fixed part, said armature being attractable to andreleasable from said field member, a carrier element pivotally mountedon said armature, a movable contact mounted on said carrier elementpivotal about an axis spaced apart from the axis of said carrierelement, a relatively stationary fixed contact, first spring meansbiasing said movable contact relative to said carrier element, to agiven limit in the direction towards said fixed contact, and secondspring means biasing said carrier element relative to said armature to agiven limit in the direction to move said movable contact towards saidfixed contact, said carrier element being movable in opposition to saidsecond spring means to another given limit, the movement of saidarmature, when attracted to said field member, being in the direction tomove said movable contact to said fixed contact, whereby, uponengagement of said movable contact with said fixed contact in responseto the movement of said armature to the attracted position,

said second spring means initially yields to the extent of said othergiven limit of said carrier element, before the armature has reached itsfinal position, and subsequently recovers to the first named given limitof said carrier element, leaving said first spring means in a conditionof yield.

4. An electromagnetic contactor, comprising a field member, an armaturehaving a hole, said armature being movably mounted on a fixed part andattractable and releasable from said field member, a carrier elementpivotally mounted on said armature, said carrier element comprising twoplates mounted one each side of said armature, a bar coupling saidplates, parallel to and spaced from the pivot axis of said carrierelement, said bar passing through said hole in the armature, said holebeing large enough to afford play of said bar therein,

a movable contact pivotally mounted on said carrier element, arelatively stationary fixed contact, first spring means biasing saidmovable contact relative to said carrier element to a given limit in thedirection towards said fixed contact, and second spring means biasingsaid carrier element relative to said armature, in the direction to movesaid movable contact towards said fixed contact, to a limit asdetermined by said bar abutting against one side of said hole, themovement of said armature, when attracted to said field element, beingin the direction to move said movable contact to said fixed contact,whereby, upon engagement of said movable contact with said fixedcontact, in response to the movement of said armature to the attractedposition, said second spring means initially yield to the limit asdetermined by said bar abutting against the other side of said hole,before the armature has reached its final position, and subsequentlyrecover to the limit determined by the abutting of said bar against thefirst-named side of said hole, leaving said first spring means in acondition of yield.

References Cited in the file of this patent UNITED STATES PATENTS1,280,661 Carichofi Oct. 8, 1918 1,309,822 Steen July 15, 1919 1,729,876James et al. Oct. 1, 1929 1,763,116 White June 10, 1930 1,779,659Carichofi Oct. 28, 1930 2,071,595 Trofimov Feb. 23, 1937 2,145,327 VanValkenburg Jan. 31, 1939 2,231,974 Van Valkenburg Feb. 18, 19412,255,886 Hudson Sept. 16, 1941 2,424,308 Ellis et a1. July 22, 19472,524,287 Ellis Oct. 3, 1950 FOREIGN PATENTS 434,000 Germany Aug 2, 1925

